package my_linkedlist;/*
 *@ 代阳敲的专属代码
 **/

public class ListNode {
     int val;
   ListNode next;
 ListNode() {}
     ListNode(int val) { this.val = val; }
    ListNode(int val, ListNode next) { this.val = val; this.next = next; }
}

class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        if (list1 == null) {
            return list2;
        }
        if (list2 == null) {
            return list1;
        }
        ListNode head = null;
        if (list1.val <= list2.val) {
            head = list1;
            list1 = list1.next;
        } else {
            head = list2;
            list2 = list2.next;
        }
        ListNode cur = head;
        while (list1!= null || list2 != null) {
            if (list1.val <= list2.val) {
                cur.next = list1;
                cur = cur.next;
                list1 = list1.next;
            } else {
                cur.next = list2;
                cur = cur.next;
                list2 = list2.next;
            }
        }
        if (list1 != null) {
            cur.next = list1;
            cur = cur.next;
        }
        if (list2 != null) {
            cur.next = list2;
            cur = cur.next;
        }
        return head;

    }

    public static void main(String[] args) {
        ListNode l1 = new ListNode(1, new ListNode(2, new ListNode(4)));
        ListNode l2 = new ListNode(1, new ListNode(3, new ListNode(4)));
        Solution solution = new Solution();
        solution.mergeTwoLists(l1, l2);

    }
}